With buffets available nearly 24 hours a day, it's no surprise that the average cruise-goer gains a pound a day, according to a poll of 1,281 people by independent cruise travel agents. Of those polled, 6 percent said they gained up to 18 pounds during their two-week cruise.

But cruise lines are working hard to stop passengers from weighing down the boat. They've added fun fitness programs and cardio-intensive activities so you can eat your cake from the dessert cafe — and fit into your evening gown too.

Classes, running

Cruise line: Princess Cruise Line

Ship: Royal Princess

Route: Choose among various European cruises and Caribbean cruises depending on the date.

Fitness perk: This new ship, which will make its debut in June, has a double-lane jogging track so runners won't be bothered by walkers. There will be outdoor exercise stations throughout the track with weight machines and resistance training offerings so you can get in your interval training. If you want a break from your run, check out one of the new fitness classes. Choose between TRX (suspension training body-weight exercises created from the U.S. Navy SEALs workout), a spin class or a Chi Balls class (use aromatherapy balls during yoga for extra relaxation or stimulation).

Circulation

Cruise line: Seabourn Cruise Line

Ships: Sojourn and Quest

Route: They take various routes throughout the world depending on the date.

Fitness perk: These ships contain a Kneipp Walk Pool. This shallow, circular pool is separated into regions of very warm and very cold water. The combination of changing pressures, temperatures and motion is believed to improve your capillary circulation if you walk around the pool. It's also supposed to help cleanse toxins from your body, increase hormonal balance and reduce stress.

Kinesis wall

Cruise line: Seabourn Cruise Line

Ships: Odyssey, Sojourn and Quest

Route: They take various routes throughout the world depending on the date.

Fitness perk: They have a Kinesis wall system on all three ships. It's an innovative system that uses cables and pulleys to create a consistent effort throughout a range of motions.